The zeolites are microporous crystalline materials of variable composition, characterized by a crystal lattice of TO.sub.4 tetrahedrons (where T represents atoms with formal oxidation status of +3 or +4, as for example Si, Ti, Al, Ge, B, Ga, . . . ) that share all their vertexes causing a tridimensional structure which contains channels and/or cavities of molecular dimentions. When any of the T atoms present an oxidation status smaller than +4, the crystal lattice which is formed, presents negative charges which are compensated by means of the presence in the channels or cavities of organic or inorganic cations. In said channels and cavities, organic and H.sub.2 O molecules may also be housed, due to which, in general, the chemical composition of the zeolites may be represented by means of the following empirical formula: EQU x(M.sub.1/n XO.sub.2):yYO.sub.2 :zR:wH.sub.2 O
where, M is one or various organic or inorganic cations of +n charge; x is one or various trivalent elements; Y is one or various tetravalent elements, generally Si; and R is one or various organic substances. Though the nature of M, X, Y and R and the values of x, y, z, and w may, in general, be varied by means of postsynthesis treatments, the chemical composition of a zeolite (as synthetized or after its roasting) possesses a characteristic range of each zeolite and of its method of obtention.
On the other hand, a zeolite is also characterized by its crystalline structure, which defines a system of channels and cavities and which cause a diffraction pattern of specific X-rays. In this manner, the zeolites are differentiated from each other by their chemical composition range plus their X ray diffraction pattern. Both characteristics (crystalline structure and chemical composition) also determine the physio-chemical properties of each zeolite and their applicability in different industrial processes.